(1) Field of the Invention
This invention relates to machine tool holders, and more particularly to mechanisms for rotating an individual tool against a member being turned so as to present successive new edges against the member being machined.
(2) Prior Art
The machine tool industry has in recent years been attempting to automate their operations and minimize their machine cycle time. In machining the diameter or turning down a shaft of some sort, the tool which we are involved with here is a disc-like cutting tool having at least one sharpened peripheral edge which does the cutting and which has had to have been manually loosened and discarded after it has become worn, and a new tool inserted into the cutting tool support of the machine. This maximized the cycle time of the operation, wherein the machine operator exchanged the cutting tool insert on a machine as needed during a series of operations on an item being turned.
An advance in the art was introduced by Sandvik, Inc. on their T-Max Automatic profiling machine, wherein the tool that does the actual cutting of the item being turned, is fed, in shotgun magazine fashion, to a clamp on the machine. Once the proper quantity of material has been removed/or the tool has been worn down along only a small arcuate portion thereof, to a point of permitting no further cutting action, it is ejected and replaced automatically by a fresh tool fed from the magazine supply. This approach is unsatisfactory, because the tools are used-up somewhat prematurely. The cutting tools in these turning machines may be disc-shaped, and have at least one peripheral edge which is capable of being used in its entirety. The manual operation of loosening the tool in the machine arm, and then rotating the tool and retightening it did not waste the tools, but it certainly added to a long cycle time for an average workpice, especially when the same tool may otherwise be partially rotated as many as twenty four times and still have the same cutting or machining capabilities as about twenty four other cutting tools. Thus, the manual operation may use twenty-odd fewer tool bits, saving money at that expense, but the cycle time is longer, because the machine operator has to work to continually readjust the tool accordingly.
It is thus an object of the present invention, to provide a tool indexing mechanism which overcomes the objections of both the manual procedure and the automated procedure of tool maintenance, which was an expensive feature of prior art metal turning machines.
It is a further object of the present invention, to provide a tool indexing mechanism for metal turning machines, which will get full use of any tool used therewith.
It is yet a further object of the present invention, to provide a tool indexing mechanism which will minimize the machine operator's time for changing tools.